<!DOCTYPE html>
<html lang="en">
	<head>
		<meta charset="UTF-8" />
		<meta name="viewport" content="width=device-width, initial-scale=1.0" />
		<title>map</title>
	</head>
	<body>
		<script>
			const map = new Map()
			map.set(undefined, 'undefined')
			map.set(null, 'null')
			const a = { c: '1' }
			const b = a
			map.set(a, 1)
			map.set(b, 2)
			console.log('map', map, map.get(undefined), map.get(null))
		</script>
	</body>
</html>
